Design description of the Tangaye Village photovoltaic power system

The engineering design of a stand alone photovoltaic (PV) powered grain mill and water pump for the village of Tangaye, Upper Volta is described. The socioeconomic effects of reducing the time required by women in rural areas for drawing water and grinding grain were studied. The suitability of photovoltaic technology for use in rural areas by people of limited technical training was demonstrated. The PV system consists of a 1.8-kW (peak) solar cell array, 540 ampere hours of battery storage, instrumentation, automatic controls, and a data collection and storage system. The PV system is situated near an improved village well and supplies d.c. power to a grain mill and a water pump. The array is located in a fenced area and the mill, battery, instruments, controls, and data system are in a mill building. A water storage tank is located near the well. The system employs automatic controls which provide battery charge regulation and system over and under voltage protection. This report includes descriptions of the engineering design of the system and of the load that it serves; a discussion of PV array and battery sizing methodology; descriptions of the mechanical and electrical designs including the array, battery, controls, and instrumentation; and a discussion of the safety features. The system became operational on March 1, 1979

Operational performance of the photovoltaic-powered grain mill and water pump at Tangaye, Burkina Faso (formerly Upper Volta)

A photovoltaic (PV) system powering a grain mill and water pump was installed in the remote African village of Tangaye, Burkina Faso (formerly Upper Volta) under the sponsorship of the U.S. Agency for International Development (AID) and by the National Aeronautics and Space Administration (NASA) Lewis Research Center (LeRC) in early 1979. The presence reports covers the second two years of operation from April 1981 through June 1983. During this time, the grain mill and water pump were operational 96 and 88 percent of the time respectively, and the PV system generated sufficient electricity to enable the grinding of about 111 metric tons of finely ground flow and the pumping of over 5000 cm sq of water from the 10 m deep well. The report includes a description of the current configuration of the system, a review of system performance, a discussion of the socioeconomic impact of the system on the villagers and a summary of results and conclusions covering the entire four-year period

Smooth empirical Bayes estimation of observation error variances in linear systems

A smooth empirical Bayes estimator was developed for estimating the unknown random scale component of each of a set of observation error variances. It is shown that the estimator possesses a smaller average squared error loss than other estimators for a discrete time linear system

Operational performance of the photovoltaic-powered grain mill and water pump at Tangaye, Upper Volta

The first two years of operation of a stand alone photovoltaic (PV) power system for the village of Tangaye, Upper Volta in West Africa are described. The purpose of the experiment was to demonstrate that PV systems could provide reliable electrical power for multiple use applications in remote areas where local technical expertise is limited. The 1.8 kW (peak) power system supplies 120-V (d.c.) electrical power to operate a grain mill, a water pump, and mill building lights for the village. The system was initially sized to pump a part of the village water requirements from an existing improved well, and to meet a portion of the village grain grinding requirements. The data, observations, experiences, and conclusions developed during the first two years of operation are discussed. Reports of tests of the mills used in the project are included

Tunisia Renewable Energy Project systems description report

In 1979, the Agency for International Development (AID) initiated a renewable energy project with the Government of Tunisia to develop an institutional capability to plan and institute renewable energy technologies in a rural area. The specific objective of the district energy applications subproject was to demonstrate solar and wind energy systems in a rural village setting. The NASA Lewis Research Center was asked by the AID Near East Bureau to manage and implement this subproject. This report describes the project and gives detailed desciptions of the various systems

Detecting trends and patterns in reliability data over time using exponentially weighted moving-averages

A simple, easy-to-use graphical method is presented for use in determining if there is any statistically significant trend or pattern over time in an underlying Poisson event rate of occurrence or binomial failure on demand probability. The method is based on the combined use of both an exponentially weighted moving-average (EWMA) and a Shewhart chart. Two nuclear power plant examples are introduced and used to illustrate the method. The false alarm probability and power when using the combined procedure are also determined for both cases using Monte Carlo simulation. The results indicate that the combined procedure is quite effective in rapidly detecting either a small or large step increase in the Poisson rate or binomial probability over time

Comparing PRAs with operating experience

Probabilistic Risk Assessment is widely used to estimate the frequencies of rare events, such as nuclear power plant accidents. An obvious question concerns the extent to which PRAs conform to operating experience--that is, do PRAs agree with reality? The authors discuss a formal methodology to address this issue and examine its performance using plant-specific data